Process for preparing 2, 2, 4, 4-tetraalkyl-3-hydroxy-3-butenoic acid beta-lactones



United States Patent PROCESS FOR PREPARING 2,2,4,4-TETRAALKYL- 3-HYDROXY-3-BUTENOIC ACID fi-LACTONES Edward U. Elam, Kingsport, Tenth, assiguor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Nov. 4, 1963, Ser. No. 321,280 9 Claims. (Cl. 26il343.9

wherein R and R each represent lower alkyl groups of from 1 to 4 carbon atoms, such as methyl, ethyl propyl, isopropyl and butyl as present in lower dialltylketenes such as dirnethylketene, or R and R are joined alkylene groups which together with the carbon atom to which they are attached represent a saturated carbocyclic ring of to 6 carbon atoms, e.g. as in tetramethylene ketene and pentamethylene ketene. (R) P represents an organic tri valent phosphorus derivative catalyst including a phosphine, phosphite, phosphinite or phosphonite catalyst in which R represents either lower alkyl of l to 4 carbon atoms such as present in the trialkylphosphines such as trimethyl, triethyl, tripropyl and tributyl phosphines, e.g. tributylphosphine (C H P; or R represents lower alkoxy of l to 4 carbon atoms such as present in trialkyl phosphites, such as trimethyl, triethyl, tripropyl and tributyl phosphites, e.g. triethylphosphite (C H O) P (dialkyl phosphitcs which are pentavalent phosphorus derivatives are not useful); or R represents a benzene radical including phenyl and substituted phenyl suchas present in the triarylphosphines, e.g. triphenyl phosphine (C H P and tri(chlorophenyl)ph0sphine (Cl-C H P; or R represents a benzoxy radical such as present in triarylphosphites, e.g. triphenylphosphite (C H O) P and tri(chlorophenoxy)phosphite (ClC H.,O) P, or in (R) P at least one R can be lower alkoxy and the other two are benzene radicals such as present in mixed alkyl aryl phosphinites, e. g. butyl diphenylphosphinite, (C H POC H or at least one R can be a benzene radical and the other two lower alkoxy groups such as present in alkyl aryl phosphonites, eg. dibutylphenyl phosphonite, (C H O) PC H Phosphorous halides are too active for use as catalysts in the process.

The trialkylphosphines and triarylphosphines are especially useful as catalysts in the reaction although somewhat more polymerization is obtained using the phosphines with the lower molecular weight dialkylketenes such as dimethylketene.

The process is carried out by using catalytic amounts of the phosphine or phosphite compounds (R) P and allowing the reaction mixture to stand at room temperature or at elevated temperature until dimerization is complete after which the dimer can be isolated by distillation especially under reduced pressure as illustrated in the examples below. If desired, the reaction can be run at subor 'superatmospheric pressure but satisfactory results are obtainable by conducting the reaction at atmospheric pressure.

The phosphine and phosphite catalysts can be used in catalytic amounts of from about 1% or less of the weight of the charged ketene to an equirnolecular or larger amount. A preferred concentration is about 1 to 5% based on the amount of ketene used.

Reaction temperatures of from about 25 C. to the boiling point of the lactone are useful, especially 50 to 175 C.

There are a substantial number of organic solvents which can be used in the reaction, but are generally not required and the fi-lactones produced in the process are excellent solvents. Suitable solvents can be selected from the class of hydrocarbons, ethers, esters, ketones and nitriles, e.g., diethyl ether, tetrahydroiuran, tetrahydropyran, diisopropyl ether, ethylene dichloride, dioxane, benzene, toluene, xylenes, ethylbenzene, chloro-benzene, acetonitrile, ethyl acetate, isopropyl acetate, isobutyl acetate, methyl isobutyrate, di(2-ethylhexyl)phthalate, acetone, methyl isoamyl ketone, and the like.

Mixed B-lactones produced in the process by dimerization of mixtures of dialkylketenes are contemplated by the invention. Thus, a mixture of dimethyl and diethylketenes yields a fl-lactone of the above formula where one pair of R and R groups are methyl groups and the other pair are ethyl groups.

Representative dialkylketenes of formula R R &@O are for example dimethylketene, ethylmethylketene, diethylketene, methylpropylketene, iso'butylethylketene, butylethylketene, tetramethyleneketene and pentamethyleneketene.

The following examples will serve to illustrate the invent-ion.

Example I Five grams of triethyl phosphite were placed in a 1-liter three-necked flask which was fitted with a Dry lce-cooled reflux condenser, thermometer, inlet for dimethylketene, and a magnetic stirrer. Stirring was started and dimethylketene was passed in. A strongly exothermic reaction occurred and the temperature rose spontaneously to to C. and remained there until the d-irnethylketene stream was shut off. A total of approximately 300 grams of product had collected. Gas chromatographic analysis of this crude product indicated that it contained 97% of 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid B-lactone and 3% of tetramethyl-l-,3-cyclobutanedione. Distillation gave, after removal of a small amount of low-boilers containing tetramethyl-1,3-cyclobutanedione, and 15 m1. of forecut, B.P. 76,578.5 C. (25 mm), n 1.4368, 235 ml. of pure 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid {:7- lactone, B.P. 78.59 C. (25 mm), n 1.4380, the infrared spectrum of which was identical with that of authentic material. Volume of the residue was 20 ml. The lactone has the formula O C=O Example 2 The procedure of Example 1 was repeated except that 5 g. of triphenyl phosphite (C H OMP was used as the catalyst. The generator was shut down after about 250 ml. of dimethylketene had been collected. reaction in this case was only slightly exothermic and some solid tetramethyl-1,3 cyclobutanedione was formed. The liquid present was taken up in ether and separated from the solid by filtration. Gas chromatography of the filtrate indicated that 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid B-lactone was present.

Example 3 The procedure of Example 1 was repeated with g. of triphenylphosphine (C H P dissolved in 50 ml. of xylene as the catalyst. A quantity of sticky polymer Was formed in this reaction, but gas chromatography of the liquid portion of the product indicated that S-hydroxy- 2,2,4-trimethyl-3-pentenoic acid B-lactone was also present.

Example 4 Ten grams of triethyl phosphite (C H O) P was placed in a 250 ml. three-necked flask equipped with a magnetic stirrer, reflux condenser, thermometer, and a dropping funnel, and 100 g. of butylethylketene was added gradually. An initial highly exothermic reaction carried the temperature to 140 C. The mixture was heated to 165+70 C. overnight. Distillation of the product gave 71 g. boiling from 12'16 C. at 2.5-3 mm., 11;, l.45511.4554. The infrared absorption spectrum of this material indicated that it was 2-butyl-2,4adiethyl-3-hydroxy-3-octenoic acid li-lactone, having the formula Example 5 The procedure of Example 3 was repeated except using 5 g of tributylphosphine as the catalyst to obtain some 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid fi-lactone and considerable polymer. Monoand dibutylphosphine give similar results.

Example 6 Example 7 The procedure of Example 3 Was followed except using 5 ml. of diphenyl decyl phosphite as catalyst. A smaller amount of 3 hydroxy-2,2,4-trimethyl-3-pentenoic acid 18- lactone was formed.

Example 8 The procedure of Example 6 wasfollowed except using 5 ml. of dibutyl phenyl phosphonite, (C H O) PC H as the catalyst. The product contained 89% of S-hydroxy 2,2,4-trimethyl-3-pentenoic acid B-lactone and 11% of 2,2,4,4-tetramethyl- 1,3-cyclobutanedione.

Example 9 Substitution a butyl diphenylphosphinite as the catalyst in the procedure of Example 8 gives similar results.

Example A sample of pentamethyleneketene was dimerized inthe presence of a catalytic amount of triethyl phosphite. The characteristic absorption bands of an unsaturated The A fi-lactone were detected in the infrared spectrum of the reaction product.

Example 11 Approximately 5 ml. of freshly distilled butylethylketene was placed in a test tube and a drop of the organic trivalent phosphorus derivative catalyst, hexamethylphosphorous triamide, P[N(CH was added. The mixture became hot and gradually set to a sticky solid. Although this material was mostly polymeric, its infrared spectrum contained a band at 535 which is a highly characteristic feature of the spectra of 2,2,4-,4-tetraalky1- 3-butenoic acid B-lactones. In addition to this band, all of the principal bands of the spectrum of an authentic specimen of the fl-lactone dimer of butylethylketene were present. Similar results are obtained by using the amides of phosphonous acid, such as C H P(NC H and of phosphinous acid, such as C H (4-MeC H )PNHC H as catalysts for the dimerization In the manner of the above examples the other lower diaikyl ketenes and mixtures of diiferent dialkyl ketenes can be used to produce the corresponding 3-hydroxy- 2,2,4-trialkyl-3-alkenoi-c B-lactones using the organic trivalent phosphorus compounds, especially the phosphines and phosphites, phosphinites and phosphonites described above as catalysts.

The invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be efiected within the spirit and scope of the invention as described hereinabove, and as defined in the appended claims.

What I claim is:

1. A process of preparing a 9-lactone which comprises contacting a disubstituted ketene having the general formula wherein R and R are selected from the class consisting of lower alkyl and alkylene groups which together with the carbon atom to which they are attached form a saturated carbocyclic ring of 5 to 6 carbon atoms, with a catalytic amount of a member of the class consisting of phosphine, phosphite, phosphinite and phosphonite compounds having the formula wherein R represents a member of the class consisting of lower alkyl, lower alkoxy, a benzene radical and a benzoxy radical.

2. A process of preparing a S-lactone which comprises contacting a lower dialkylketene with a catalytic amount of a lower trialkylphosphine.

3. A process of preparing a ,B-lactone which comprises contacting dimethylketene with a catalytic amount of tributylphosphine thereby forming 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid ,B-lactone.

4. A process of preparing a fi-lactone which comprises contacting dimethylketene .With a catalytic. amount of triphenylphosphine thereby forming 3-hy-droxy-2,2,4-trimethyl-31pentenoic B-lactone.

5. A process of preparing a B-lactone which comprises.

I contacting dimethylketene with a catalytic amount of triphenylphosphine thereby forming 3-hydroxy-2,2,4-trimethyI-S-pentenoic fl-lactone.

6. A process of preparing a ,H-lactone which comprises contacting a lower dialkylketene with a catalytic amount of a lower trialkylphosphite. V

7. A process of preparing a B-lactone which comprises contacting dimethylketene with a catalytic amount of triethylphosphite thereby forming 3-hydroxy-2,2,4-tri- V methyl-3-pentenoic B-lactone.

5 triefliylphosphite thereby forming 2-buty1-2,4-diethy1-3- hydroXy-3octenoic fi-lactone.

9. A process for preparing a ;3-1actone which comprises contacting a lower dialkylketene with a catalytic amount of dibutyl phenyi phosphonite.

References Cited by the Examiner UNITED STATES PATENTS 3,062,836 11/1962 Martin 260-343.9

6 OTHER REFERENCES Cram et a1.: Organic Chemistry, McGraw-Hill Book Co., New York (1959), page 179.

Mellors Modern Inorganic Chemistry, Longmans, Green and Co., New York (1939), pages 761-764.

WALTER A. MODANCE, Primary Examiner. NICHOLAS s. RIZZO, Examiner. 

1. A PROCESS FOR PREPARING A B-LACTONE WHICH COMPRISES CONTACTING A DISUBSTITUTED KETENE HAVING THE GENERAL FORMULA 